The present invention pertains generally to electronic circuit cooling, and more particularly, to a self-actuated damper and actuation mechanism for preventing air flow through empty slots of a module circuit board cage.
Proper airflow across a printed circuit board (PCB) is important for transferring heat away from the electronic components. PCBs are used in a wide variety of electronic equipment, especially equipment incorporating microprocessors, which can generate significant amounts of heat. Typically, such PCBs include one or more microprocessors and other heat-generating components, with one or more heat sinks also mounted on the board. Conventional cooling techniques employ a fan or blower to direct a tangential flow of air across the PC board and heat sinks, to cool the components by convection.
Heat dissipation is a more difficult problem to address when the electronic equipment incorporates numerous microprocessors or other components and modules generating large amounts of heat. Some high-end servers, for example, can house assemblies containing as many as 64 microprocessors, with associated memory devices and ASICs, dissipating up to 12 kilowatts. Unless properly addressed, the heat dissipated by these large assemblies can cause component damage. Accordingly, the importance of proper cooling through methods such as the use of heat sinks, air-cooling fans, and liquid cooling methods, is ever increasing.
PCB assemblies, also referred to herein as card board assemblies, are often housed with other like assemblies in a modular cage which provides a common cooling system for each of the card board assemblies inserted in the cage. In a modular assembly comprising one to many circuit boards, both the presence and placement of the number of boards can affect the evenness of the airflow across each of the boards. In a system utilizing air coolant fans to generate air flow across the assemblies housed in the cage through air flow entrances on one side and out air flow exits on the opposite side, the air flow is generally distributed evenly across each of the assemblies in the cage if the cage is full (i.e., each slot contains a card board assembly). However, if one or more slots are empty, air forced in one side of the cage by the fans will, unless otherwise manipulated, generally flow through the path of least resistancexe2x80x94namely, through the empty slot(s) and out the air flow exits of the empty slots. Thus, when one or more slots are empty, significant amounts of air flow will generally bypass the card assembly boards that are housed in the cage, causing improper cooling of these assemblies. Accordingly, a need exists for ensuring delivery of more evenly distributed air flow in multi-slot PCB assembly cages regardless of the number and positions of card board assemblies inserted in the cage.
Prior art fan cooling methods address this problem by increasing the power of the fans and/or through adjusting the placement of the fans. In an ideal fan cooling system for a modular assembly, the design should be such to ensure even airflow across all PCBs present in the assembly, regardless of the number and placement of the boards. This method, however, requires higher power consumption and may not necessarily provide proper cooling levels to all assemblies. Accordingly, a need exists for a method for providing proper and even cooling across all assemblies present in the cage without the application of higher power fans.